The present invention relates generally to an electric plug for a power cord and more particularly to an electric plug for a power cord which includes a circuit breaking device.
An electric plug commonly includes a plurality of conductive terminals which are sized and shaped to project into associated receptacles in an electrical outlet. The electric plug is typically formed onto the first end of a power cord. The second end of the power cord is traditionally connected to a load (e.g., a conventional electrical appliance). As an example, the second end of a power cord may be directly hardwired to the power circuit for the load. As another example, the second end of a power cord may be in the form of one or more female receptacles (i.e, in the case of an extension cord) into which a plug for the load is connected. With the electric plug for a power cord inserted into a properly functioning electrical outlet, current travels from the power source, into the outlet, through the plug, along the length of the power cord and into desired load, thereby providing the necessary electrical power for said load to operate.
Circuit breakers are well known in the art and are commonly provided along the current path to protect the load against overcurrent conditions. Specifically, a circuit breaker monitors the amount of current passing into and traveling out from a load. Whenever the amounts of incoming and outgoing current passing into and traveling out from the load exceeds the current rating of the circuit breaker (thereby signifying an overcurrent condition) or if there is an accidental short circuit in the load, the circuit breaker is opened, or tripped, thereby instantly cutting off the flow of electricity to the load, which is highly desirable. When the overload condition is eliminated, the circuit breaker can be manually reset which, in turn, restores the flow of electricity to the load.
Conventionally, circuit breakers are centrally located, particularly in a domestic establishment, with at least one circuit breaker having an average capacity of approximately 15 amperes governing each circuit.
Centrally locating circuit breakers has been found to be highly undesirable in that the amperage capacity of a centrally located circuit breaker may be excessive and the protection afforded thereby may hence be inadequate for a load with a critical power rating below that capacity. As such, the circuit breaker would fail to adequately protect against a current overload which is less than that required to open the circuit breaker but which is still large enough to considerably damage the load.
Accordingly, it is known in the art for individual circuit breakers to be integrated directly into each electric plug of a power cord.
As an example, U.S. Pat. No. 4,307,925 to D. Drew discloses a plug connector with a circuit breaker, the plug connector being engageable with an electrical outlet. The plug connector comprises an insulating body that encapsulates circuitry for providing pathways for electrical current delivered by the connector to an associated power cord. The plug connector also comprises a deep, blind-end, socket for an elongated circuit breaker. A gap is located in the circuitry for interrupting the pathway, both terminals of the gap being in position at the blind-end of the socket so as to be bridged by the circuit breaker.
As another example, U.S. Pat. No. 4,771,367 to M. J. Serr et al. discloses an injection-molded electric plug having an integral circuit breaker. The plug housing is molded directly onto the power cord and defines a circuit breaker chamber. A circuit breaker is slidably received within the chamber and is retained therein by spring fingers. The housing is elongated and the prongs extend from one of the long sides thereof so that the housing lays substantially flat against a receptacle. The prongs are angularly oriented with respect to the elongated body so that the body with not overlie adjacent receptacle outlets.
Although well known in commerce, electric plugs which include a circuit breaker often suffer from a number of notable drawbacks.
As a first drawback, electric plugs which include a circuit breaker do not provide a readily detectable indicator for notifying the user that an overcurrent condition has been detected by the circuit breaker and that, in turn, the circuit breaker has interrupted the supply of electricity to the appliance, which is highly undesirable. As a result, the consumer would not be made aware that an overcurrent condition has opened up, or tripped, the circuit breaker in the plug until such time that the user is required to use the electrical appliance and recognizes power is no longer being supplied thereto, which is highly undesirable.
As a second drawback, electric plugs which include a circuit breaker do not enable the consumer to manually open the circuit which, in turn, interrupts the supply of electricity to the appliance, which is highly undesirable. Specifically, it has been found that in certain circumstances the consumer would want the supply of electricity to the appliance to be temporarily interrupted (e.g., when repairing, maintaining or upgrading the appliance). In the absence of a manually operable switch, the user is required to physically remove the plug from the electrical outlet, which is considerably time consuming and labor intensive.
As a third drawback, electric plugs which include a circuit breaker often include a small push-button for manually resetting (i.e., closing) the circuit after the circuit interrupter experiences a trip condition, which is highly undesirable. As can be appreciated, the manual actuation of a small push-button does not provide the consumer with an adequate tactile physical response as to whether the push-button was properly depressed.
As a fourth drawback, electric plugs which include a circuit breaker are not typically constructed for outdoor use, which is highly undesirable. Specifically, electric plugs which include a circuit breaker are not typically water resistant, thereby limiting their range of potential applications.
It is an object of the present invention to provide a new and improved electric plug for a power cord.
It is another object of the present invention to provide an electric plug as described above which includes a circuit interrupter that trips in response to overcurrent conditions.
It is yet another object of the present invention to provide an electric plug as described above which includes a readily detectable indicator for notifying the user that the circuit interrupter has tripped in response to an overcurrent condition.
It is still another object of the present invention to provide an electric plug as described above which enables the user to manually interrupt the flow of electricity through said electric plug.
It is yet still another object of the present invention to provide an electric plug as described above which includes means for manually resetting the circuit interrupter after a tripped condition, said means providing adequate tactile response for the user.
It is another object of the present invention to provide an electric plug as described above which is constructed for outdoor use.
It is yet another object of the present invention to provide an electric plug as described above which may be mass produced, has a minimal number of parts, and can be easily assembled.
Accordingly, as one feature of the present invention, there is provided an electric plug for a power cord, said power cord comprising a hot line, a neutral line and a ground line, said electric plug comprising a combination circuit breaker and power switch device electrically connected to the hot and neutral lines of said power cord, and first, second and third conductive terminals, said first and second conductive terminals being electrically connected to said combination circuit breaker and power switch device, said third conductive terminal being electrically connected to said ground line, wherein said combination circuit breaker and power switch device regulates the flow of current between said first and second conductive terminals and said power cord.
As another feature of the present invention, there is provided a method of manufacturing an electric plug for a power cord, said power cord comprising a hot line, a neutral line and a ground line, said method comprising the steps of providing a combination circuit breaker and power switch device, mounting at least one protective casing onto said combination circuit breaker and power switch device, slidably disposing a transparent plastic cover over said combination circuit breaker and power switch device, fittingly disposing a heated sleeve over said transparent plastic cover to create a seal of said transparent plastic cover over said combination circuit breaker and power switch device, electrically coupling first and second terminals to said combination circuit breaker and power switch device, electrically coupling a third terminal to said ground line, and electrically coupling said combination circuit breaker and power switch device to said hot line and said neutral line, and molding a plug housing over said combination circuit breaker and power switch device.
Additional objects, as well as features and advantages, of the present invention will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practice of the invention. In the description, reference is made to the accompanying drawings which form a part thereof and in which is shown by way of illustration specific embodiments for practicing the invention. These embodiments will be described in sufficient detail to those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims.